The present invention relates to biaxially textured, composite, metallic substrates and articles made therefrom, and more particularly to such substrates and articles made by plastic deformation processes such as rolling and subsequently recrystallizing high purity cubic materials to form long lengths of biaxially textured sheets, and more particularly to the use of said biaxially textured sheets as templates to grow biaxially textured, epitaxial metal/alloy/ceramic layers.
Current materials research aimed at fabricating high-temperature superconducting ceramics in conductor configurations for bulk, practical applications, is largely focused on powder-in-tube methods. Such methods have proved quite successful for the Bixe2x80x94(Pb)xe2x80x94Srxe2x80x94Caxe2x80x94Cuxe2x80x94O (BSCCO) family of superconductors due to their unique mica-like mechanical deformation characteristics. In high magnetic fields, this family of superconductors is generally limited to applications below 30xc2x0 K. In the Rexe2x80x94Baxe2x80x94Cuxe2x80x94O (ReBCO, Re denotes a rare earth element), Tlxe2x80x94(Pb,Bi)xe2x80x94Srxe2x80x94(Ba)xe2x80x94Caxe2x80x94Cuxe2x80x94O and Hgxe2x80x94(Pb)xe2x80x94Srxe2x80x94(Ba)xe2x80x94Caxe2x80x94Cuxe2x80x94O families of superconductors, some of the compounds have much higher intrinsic limits and can be used at higher temperatures.
It has been demonstrated that these superconductors possess high critical current densities (Jc) at high temperatures when fabricated as single crystals or in essentially single-crystal form as epitaxial films on single crystal substrates such as SrTiO3 and LaAlO3. These superconductors have so far proven intractable to conventional ceramics and materials processing techniques to form long lengths of conductor with JC comparable to epitaxial films. This is primarily because of the xe2x80x9cweak-linkxe2x80x9d effect.
It has been demonstrated that in ReBCO, biaxial texture is necessary to obtain high transport critical current densities. High Jc""s have been reported in polycrystalline ReBCO in thin films deposited on special substrates on which a biaxially textured non-superconducting oxide buffer layer is first deposited using ion-beam assisted deposition (IBAD) techniques. IBAD is a slow, expensive process, and difficult to scale up for production of lengths adequate for many applications.
High Jc""s have also been reported in polycrystalline ReBCO melt-processed bulk material which contains primarily small angle grain boundaries. Melt processing is also considered too slow for production of practical lengths.
Thin-film materials having perovskite-like structures are important in superconductivity, ferroelectrics, and electro-optics. Many applications using these materials require, or would be significantly improved by, single crystal, c-axis oriented perovskite-like films grown on single-crystal or highly aligned metal or metal-coated substrates.
For instance, Yxe2x80x94Ba2xe2x80x94Cu3xe2x80x94Ox (YBCO) is an important superconducting material for the development of superconducting current leads, transmission lines, motor and magnetic windings, and other electrical conductor applications. When cooled below their transition temperature, superconducting materials have essentially no electrical resistance and carry electrical current without heating up. One technique for fabricating a superconducting wire or tape is to deposit a YBCO film on a metallic substrate. Superconducting YBCO has been deposited on polycrystalline metals in which the YBCO is c-axis oriented, but not aligned in-plane. To carry high electrical currents and remain superconducting, however, the YBCO films must be biaxially textured, preferably c-axis oriented, with effectively no large-angle grain boundaries, since such grain boundaries are detrimental to the current-carrying capability of the material. YBCO films deposited on polycrystalline metal substrates do not generally meet this criterion.
It has been demonstrated that high critical current densities can be obtained in YBCO films that have been epitaxially deposited on biaxially textured Ni. However, for practical superconductivity applications it would be desirable to have a biaxially textured metal substrate with reduced or no magnetism, with increased strength and better thermal expansion match to the superconductor.
The present invention provides a method for fabricating biaxially textured composite substrates with desirable compositions. This provides for applications involving epitaxial devices on such alloy substrates. The alloys can also be thermal expansion and lattice parameter matched by selecting appropriate compositions. They can then be processed according to the present invention, resulting in devices with high quality films with good epitaxy and minimal microcracking.
The terms xe2x80x9cprocessxe2x80x9d, xe2x80x9cmethodxe2x80x9d, and xe2x80x9ctechniquexe2x80x9d are used interchangeably herein.
For further information, refer to the following publications, the noted sections of which are incorporated herein by reference:
1. K. Sato, et al., xe2x80x9cHigh-Jc Silver-Sheathed Bi-Based Superconducting Wiresxe2x80x9d, IEEE Transactions on Magnetics, 27 (1991) 1231.
2. K. Heine, et al., xe2x80x9cHigh-Field Critical Current Densities in Bi2Sr2Ca1Cu2O8+x/Ag Wiresxe2x80x9d, Applied Physics Letters, 55 (1989) 2441.
3. R. Flukiger, et al., xe2x80x9cHigh Critical Current Densities in Bi(2223)/Ag tapesxe2x80x9d, Superconductor Science and Technology 5, (1992) S61.
4. D. Dimos et al., xe2x80x9cOrientation Dependence of Grain-Boundary Critical Currents in Y1Ba2Cu3O7 Bicrystalsxe2x80x9d, Physical Review Letters, 61 (1988) 219.
5. D. Dimos et al., xe2x80x9cSuperconducting Transport Properties of Grain Boundaries in Y1Ba2Cu3O7 Bicrystalsxe2x80x9d, Physical Review B, 41 (1990) 4038.
6. Y. Iijima, et al., xe2x80x9cStructural and Transport Properties of Biaxially Aligned YBa2Cu3O7xe2x88x92x Films on Polycrystalline Ni-Based Alloy with Ion-Beam Modified Buffer Layersxe2x80x9d, Journal of Applied Physics, 74 (1993) 1905.
7. R. P. Reade, et al. xe2x80x9cLaser Deposition of biaxially textured Yttria-Stabilized Zirconia Buffer Layers on Polycrystalline Metallic Alloys for High Critical Current Yxe2x80x94Baxe2x80x94Cuxe2x80x94O Thin Filmsxe2x80x9d, Applied Physics Letters, 61 (1992) 2231.
8. D. Dijkkamp et al., xe2x80x9cPreparation of Yxe2x80x94Baxe2x80x94Cu Oxide Superconducting Thin Films Using Pulsed Laser Evaporation from High Tc Bulk Material,xe2x80x9d Applied Physics Letters, 51, 619 (1987).
9. S. Mahajan et al., xe2x80x9cEffects of Target and Template Layer on the Properties of Highly Crystalline Superconducting a-Axis Films of YBa2Cu3O7xe2x88x92x by DC-Sputtering,xe2x80x9d Physica C, 213, 445 (1993).
10. A. Inam et al., xe2x80x9cA-axis Oriented Epitaxial YBa2Cu3O7xe2x88x92xxe2x80x94PrBa2Cu3O7xe2x88x92x Heterostructures,xe2x80x9d Applied Physics Letters, 57, 2484 (1990).
11. A. Goyal et al., xe2x80x9cHigh Critical Current Density Superconducting Tapes by Epitaxial Deposition of YBa2Cu3Ox Thick Films on Biaxially Textured Metalsxe2x80x9d, Applied Physics Letters, 69, 1795, 1996.
12. A. Goyal et al., xe2x80x9cConductors with Controlled Grain Boundaries: An Approach to the Next Generation, High Temperature Superconducting Wirexe2x80x9d, Journal of Materials Research, 12, 2924, 1997.
Hereinafter, each above listed publication is referred to by its number 1-12 enclosed in brackets.
Accordingly, it is an object of the present invention to provide new and useful biaxially textured, composite, metallic substrates and articles made therefrom.
It is another object of the present invention to provide such biaxially textured, composite, metallic substrates and articles made therefrom by plastic deformation processes including but not limited to rolling, swaging, forging, pressing, and drawing and subsequently recrystallizing high purity cubic materials to form long lengths of biaxially textured sheets, rods, wires, filaments, and other forms.
It is yet another object of the present invention to provide for the use of said biaxially textured composite forms as substrates or templates to grow epitaxial metal/alloy/ceramic layers.
Further and other objects of the present invention will become apparent from the description contained herein.
In accordance with one aspect of the present invention, the foregoing and other objects are achieved by a method of preparing a biaxially textured coated article having a cube texture which comprises the steps of: providing a metal article preform; coating at least a portion of the metal article preform with a metal coating selected from the group consisting of metals and metal alloys which produce a biaxial cube texture upon plastic deformation and subsequent recrystallization to produce a coated metal article preform; plastically deforming the coated metal article preform sufficiently that upon rapid recrystallization, a biaxial texture can be produced on the deformed surface of the metal coating; then rapidly recrystallizing at least a portion of the deformed metal coating to produce a biaxial cube texture on the recrystallized, deformed metal coating to produce a biaxially textured coated article, at least a portion of the biaxially textured coated article being characterized by non-biaxial texture.
In accordance with a second aspect of the present invention, the foregoing and other objects are achieved by a method of preparing a biaxially textured laminated article having a cube texture which comprises the steps of: providing a metal article preform; providing a metal laminate for the metal article preform comprising a metal selected from the group of consisting of metals and metal alloys which produce a biaxial cube texture upon plastic deformation and subsequent recrystallization; plastically deforming the metal laminate sufficiently that upon rapid recrystallization, a biaxial texture can be produced on the deformed surface of the metal laminate; placing the deformed metal laminate upon the metal article preform and applying conditions therebetween to bond the deformed metal laminate to the metal article preform; then rapidly recrystallizing at least a portion of the deformed metal laminate to produce a biaxial cube texture on the recrystallized, deformed metal laminate to produce a biaxially textured laminated article, at least a portion of the biaxially textured laminated article being characterized by non-biaxial texture.
In accordance with a third aspect of the present invention, the foregoing and other objects are achieved by a method of preparing a biaxially textured powder-based article having a cube texture which comprises the steps of: providing a metal tube comprising a metal selected from the group consisting of metals and metal alloys which produce a biaxial cube texture upon plastic deformation and subsequent recrystallization; filling the metal tube with metal powder to produce a powder-filled metal tube; plastically deforming the powder-filled metal tube sufficiently that upon rapid recrystallization, a biaxial texture can be produced on the deformed surface of the metal tube and sufficiently to solidify the metal powder; and rapidly recrystallizing at least a portion of the deformed metal tube to produce a biaxial cube texture on the deformed, powder-filled metal tube to produce a biaxially textured powder-based article, at least a portion of the biaxially textured powder-based article being characterized by non-biaxial texture.
In accordance with a fourth aspect of the present invention, the foregoing and other objects are achieved by a method of preparing a biaxially textured rod/plate-based article having a cube texture which comprises the steps of: providing a metal tube comprising a metal selected from the group consisting of metals and metal alloys which produce a biaxial cube texture upon plastic deformation and subsequent recrystallization; filling the metal tube with at least one of the group consisting of rods and plates to produce a rod/plate-filled metal tube; plastically deforming the rod/plate-filled metal tube sufficiently that upon rapid recrystallization, a biaxial texture can be produced on the deformed surface of the metal tube and sufficiently to solidify the at least one of the group consisting of rods and plates; and rapidly recrystallizing at least a portion of the deformed metal tube to produce a biaxial cube texture on the deformed, rod/plate-filled metal tube to produce a biaxially textured rod/plate-based article, at least a portion of the biaxially textured rod/plate-based article being characterized by non-biaxial texture.